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BalancedMixDesign(BMD)TaskForceUpdate
FHWAExpertTaskGrouponAsphaltMixtures
DAVE NEWCOMB
OurLeader
ShaneBuchanan,OldcastleMaterialsGroup
TaskForceMembers
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Name Affilation Category e-mailDaveNewcomb TexasTransportationInstitute Academia/Research [email protected] PurdueUniversity Academia/Research [email protected] UniversityofArkansas Academia/Research [email protected] LouisianaStateUniversity Academia/Research [email protected] IllinoisDOT Agency [email protected] MassachusettsDOT Agency [email protected] NevadaDOT Agency [email protected] MinnesotaDOT Agency [email protected] MaineDOT Agency [email protected] ConnecticutDOT Agency [email protected] UtahDOT Agency [email protected] MontanaDOT Agency [email protected] TexasDOT Agency [email protected] WisconsinDOT Agency [email protected] Consultant Consultant [email protected]'Angelo Consultant Consultant [email protected] Consultant Consultant [email protected] FHWA-TurnerFairbank FHWAAgency [email protected] FHWA-Denver FHWAAgency [email protected] MathyConstruction Industry [email protected] PineBluffS&G Industry [email protected] MathyConstruction Industry [email protected] HeritageResearch Industry [email protected] OldcastleMaterials Industry [email protected] OntarioMinistryofTransportation ProvincialAgency [email protected] NCAT Research [email protected]
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� NeedforBalancedMixDesign� DefineBalancedMixDesign� ReviewFHWABalancedMixDesignTaskForceEfforts
¡CurrentStateAgencyPractice¡NCHRPProblemStatementDevelopment¡TechnicalBriefDevelopmentonBalancedMixDesign
NeedforBalancedMixDesign
1890•BarberAsphaltPavingCompany•Asphaltcement12to15%/Sand70to83%/Pulverizedcarboniteoflime5to15%
1905
•CliffordRichardson,NewYorkTestingCompany•Surfacesandmix:100%passingNo.10,15%passingNo.200,9to14%asphalt•Asphalticconcreteforlowerlayers,VMAterminologyused,2.2%moreVMAthancurrentdaymixesor~0.9%higherbindercontent
1920s
•HubbardFieldMethod(CharlesHubbardandFrederickField)•Sandasphaltdesign•30blow,6”diameterwithcompressiontest(performance)asphalticconcretedesign(ModifiedHFMethod)
1927
•FrancisHveem(Caltrans)•Surfaceareafactorsusedtodeterminebindercontent;Hveemstabilometerandcohesionmeterused•Airvoidsnotusedinitially,mixesgenerallydrierrelativetoothers,fatiguecrackinganissue
1943
•BruceMarshall,MississippiHighwayDepartment•RefinedHubbardFieldmethod,standardcompactionenergywithdrophammer•Initially,onlyusedairvoidsandVFA,VMAaddedin1962;stabilityandflowutilized
1993
• Superpave• Level1(volumetric)• Level2and3(performancebased,butnever implemented)
History
http://asphaltmagazine.com/history-of-asphalt-mix-design-in-north-america-part-2/
BINDER
CONTENT
LOWER
Stability
Stability+Durability
Stability+Durability
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� Designandoptimuminterchangeable?� NOTthesame
� Manydesignbindercontents,butonlyonetrulyoptimum
� Is4%airvoidstherighttargetforeverymix?
� Optimum:thebestbindercontentforperformancerequirements/needs,andultimatelyeconomics
� Goal:Closetooptimum
Designvs.Optimum
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OldcastleSurvey
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� Mostreporteddistressesarerelatedtomixdurability.
OldcastleSurveyQuestion:Withinthepast5years,whattypeofmixperformancerelateddistresshasbeenmostevidentinyourmixes?
~40companiesrespondingfrom~30states
q Durabilityrelatedperformanceissues.q Newmaterials,newmixes
q Polymersq MoreRAP/RASq Asphaltadditivesq Etc.
q Somestatesdoing“performancetesting”duringmixdesignand/orproductiontoensureperformance.q Thisisbalancedmixdesign.
BalancedMixDesign
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PendulumofPerformance
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DRY WET
OPT
IMUM
qDefineBalancedMixDesignqDeterminethecurrent“stateofpractice”ofBMD
qPresentapproaches/conceptsforimmediateuse
qRecommendfutureneeds(potentialresearch)toadvanceBMDapproaches
qDisseminateinformation
BMDTaskForceGoals
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BMDTaskForceWorkItems
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� Completed¡ DefinitionofBalancedMixDesign¡ SurveyofAgencyCurrentPractice
÷LaboratoryBalancedMixDesignProtocols÷FieldAcceptanceProtocols
¡ ResearchProblemStatement(RPS)SubmittedtoAASHTO)
� Current¡ FHWATechnicalBriefonBalancedMixDesign
÷Draftprepared,reviewedandbeingrevised
BalancedMixDesignDefinition
• “Asphaltmixdesignusingperformancetestsonappropriatelyconditionedspecimensthataddressmultiplemodesofdistresstakingintoconsiderationmixaging,traffic,climateandlocationwithinthepavementstructure.”
• Basically,itconsistsofdesigningthemixforanintendedapplication andservicerequirement.
BalancedMixDesignDefinition
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AgencyPracticesRelatedtoBMD
McCarthy,Callans,Quigley,andScott,IIINCHRPSynthesisNo.492
AgencyApproaches
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TimAschenbrener andKevinHall
VerifiedVolDesign
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q VolumetricDesignw/PerformanceVerification–Superpave withverifyingperformanceproperties;volumetricpropertieswouldhavetofallwithinexistingM323limits.ExampleStates:Illinois,Louisiana,NewJersey,Texas,Wisconsin
PerformanceModVolDesign
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q Performance-ModifiedVolumetricDesign–initialbindercontentsetbyM323/R35;perftestingmodifiesmixtureproportions-finalvolumetricpropertiescanbeoutsideexistingM323limits.ExampleState:California
PerformanceDesign
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q PerformanceDesign– conductasuiteofperformancetestsatvaryingbindercontentsandselectthebindercontentfromtheresults.Volumetrics determinedasthe‘laststep’andreported–norequirementsforM323limits.ExampleStates:NewJerseyw/draftapproach
BMDBasicExample
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• TexasDOT• Volumetricdesignconducted• HamburgWheelTracking
Test(HWTT)AASHTOT324• OverlayTester(OT)Tex-248-F• Threeasphaltbinder
contentsareused:optimum,optimum+0.5%,andoptimum-0.5%.
• TheHWTTspecimensareshort-termconditioned.
• TheOTspecimensarelong-termconditioned.
Withinthisacceptablerange(5.3to5.8percent),themixtureattheselectedasphaltcontentmustmeettheSuperpavevolumetriccriteria.
� Performancespacediagramsshowtheperformanceofamixrelatedtomultipletests
� Allowsthemixdesignertovisualizethemixperformanceandhowtoengineerthemixtoprovidethedesiredperformance
� Illustratestheimpactofvaryingmixfactorsonperformance.
PerformanceTestingtoUnderstandMixes
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From:Performance-SpaceDiagramfortheEvaluationofHighandLowTemperatureAsphaltMixturePerformance,Buttlaretal,AAPT2016
NeedforProductionVerification
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Optimize••Localmaterialsuse,recycle,additives,cost,appropriatebindercontent••Specificsite/enduse
Establish••Performancecriteria••Potentialsurrogatetestcorrelation••Volumetricpropertybaseline
Verify••QCtesting••Volumetricscomparisontobaseline••Surrogate(“Quick”)tests••Performancetestsat“x”frequency
ProductionDesign
BMDTFWorkProducts
• RPSpreparedinJune2016• AnticipatedResults
¡ 1)reviewofthestate-of-the-practiceofmixdesign
¡ 2)reviewstate-of-the-practiceforperformancetesting,
¡ 3)developRecommendedPracticeforBalancedMixtureDesign
¡ 4)developtrainingandimplementationplanandmaterialstomoveBMDaheadinStateHighwayAgencies(SHAs).
ResearchNeedStatement
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~1MilliontonsofHMAplacedeachday.• Criticaltoaddressmixdesignin
amorecomprehensivemanner
• FavorableresponseduringAugustSOM• Status:• Rankedhigh• DecisionnottoforwardtoRAC/SCOR• PursuingNCHRP20-07Projects• Morefullydevelopworkitems• Definestateofpractice
• ProbablynextyearbeforeitisforwardedtoRAC/SCOR
ResearchNeedStatement
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• TechBriefpreparedandreviewedbyfullETG.
• SubmittedtoFHWAforpublication.
FHWATechBrief- Draft
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WhatdoWedowithThis?BalancedMix Design
Opt.AC
SetVolumetrics
Table 11 Operational Tolerances
Description Test Method Allowable Difference Between Trial Batch and JMF1 Target
Allowable Difference from Current JMF Target
Individual % retained for #8 sieve and larger Tex-200-F or
Tex-236-F
Must be within master grading limits
in Table 8
±6.01
Individual % retained for sieves smaller than #8 and larger than #200 ±4.01
% passing the #200 sieve ±2.01
Asphalt binder content, % Tex-236-F ±0.5 ±0.5
Laboratory-molded density, % Tex-207-F ±1.0 ±1.5 VMA, %, min Tex-204-F Note2 Note2
1. When within these tolerances, mixture production gradations may fall outside the master grading limits; however, the % passing the #200 will be considered out of tolerance when outside the master grading limits.
2. Mixture is required to meet Table 8 requirements.
QCVolumetrics
QAVolumetricsQAPerformance
Testing
SomeDay
SetTolerances
� KeyFoundationalPointstoKeepinMind1. “UseWhatWorks”2. “EliminateWhatDoesn’t”3. “BeasSimpleasPossible,Be
Practical,andBeCorrect”
FinalThoughtsonMixDesign
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www.asphalttechnology.org/membership
At the 2016 AAPT Meeting:
§ Leading Edge Workshop: Cracking Tests§ 5 Presentations on Cracking Tests§ Symposium: Balanced Mix Design§ 5 Presentations on High RAP/RAS§ Implementation of Specifications§ Aging Behavior§ Forum Topic: World Asphalt Market
2017 Meeting: Newport Beach, CAMarch 19-27
WebinarSeriesDescriptionAAPTandtheAsphaltInstitutearehostingathree-partwebinarseriesforunderstandingoffatiguecrackingandacomprehensivereviewofthelaboratorymethodsforfatiguecrackingtests.
ComplimentaryforAAPTMembers!
ThoughtsandQuestions?
http://www.pennyauctionwatch.com/
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